The present invention relates to a counter-rotating axial-flow fan used to cool an interior of an electric appliance.
As an electric appliance becomes smaller in size, so does a space inside a case of the electric appliance in which air flows. To cool an interior of the small case, a fan with features of a large amount of air and a high static pressure is called for. As a fan with such features, a counter-rotating axial-flow fan has come to be used in recent years.
For example, Japanese Patent Publication No. 2004-278370 (US2005/0106026) (FIG. 1) shows a conventional counter-rotating axial-flow fan of this kind.
In recent years some applications call for higher performance than that of the existing counter-rotating axial-flow fan.